[Not Applicable]
1. Field of the Invention
The present invention relates to a dual curable coating for a substrate. More specifically, the present invention relates to a top coating for a golf ball that has dual curability.
2. Description of the Related Art
Top coats are used on the exterior surfaces of a variety of substrates. Top coats serve to enhance the aesthetic appearance of the substrate as well as act as a barrier to protect the substrate from weathering, mechanical agitation and the like. One such substrate in which top coats are of particular importance is a golf ball.
A golf ball generally comprises a one-piece construction or it may include several layers including a core and an outer cover surrounding the core. Typically, one or more layers of paint and/or topcoat are applied to the exterior surface of the golf ball. For example, in one typical design, the exterior surface of the golf ball is first painted with at least one clear or pigmented base coat primer along with at least one application of a top coat. The basecoat and/or primer and top coat are applied to the golf ball to enhance the aesthetic appearance of the ball as well as mask or cover surface blemishes that may have resulted from the manufacturing process. The top coat is particularly important, in that the coat protects any markings, trademarks, logos, or the like that may be placed on the exterior surface of the ball.
Typically, the outer coating layers of a golf ball comprise a primer along with a clear urethane top coat. For example, U.S. Pat. No. 5,459,220 discloses a two-pack urethane top coat for a golf ball that uses separate packages of a polyol and diisocyanate that employs biurets and isocyanurate trimers of hexamethylene diisocyanate (HDI) as the crosslinking agents. U.S. Pat. No. 5,409,233 discloses a clear coating for use on a golf ball that incorporates a solvent system that includes methylamyl ketone.
Logos or indicia for a golf ball have been applied to the top coat surface instead of the base coat surface. Such a golf ball is disclosed in Yamana, Japanese Laid Open Patent Application Number 60-141584 for Printing Method For Golf Balls, which was filed in Japan in 1983. The Yamana patent discloses an ultraviolet (UV) light curable ink for the logo, and also discloses applying the logo to top coat. The UV light curable ink (urethane modified acrylic resin type ink) disclosed in the Yamana patent was manufactured by Toyo ink and the ink had sufficient durability to be used on a playable golf ball based on the absence of chipping and the retention of the logo after 50 hits against a steel plate at 45 meters per second.
Another example of a logo applied to the top coat is Shapiro et al., U.S. Pat. No. 5,785,612, for a Golf Ball, which was filed in 1996. The Shapiro patent discloses indicia formed from an UV light curable ink, and which is applied to a golf ball only having a top coat on the cover.
In the development of top coats, the primary issue is related to the adhesion of the top coat to the base coat, or the cover of the golf ball. The logo or indicia has been designed to adhere to the base coat or the top coat. However, the golf ball industry has yet to address providing for adherence of the top coat to the logo or indicia, particularly a logo or indicia based on a UV light curable ink.
The present invention provides a solution to the problem of adhesion of indicia to a top coat. The present invention is able to resolve this problem by providing a top coat having a dual curable compound.
One aspect of the present invention is a coating for a golf ball having pentaerythritol triacrylate. Another aspect of the present invention is a golf ball having a cover, a base coat on the cover and a top coat on the base coat. The top coat includes a polyisocyanate component and a polyol component. The polyol component includes a dual-curing component in an amount ranging from 2 to 10 part per weight of the polyol component. The dual curing component may be pentaerythritol triacrylate, or a mixture of pentaerythritol mono-acrylate, pentaerythritol di-acrylate, pentaerythritol triacrylate and/or pentaerythritol tetraacrylate.
Yet another aspect of the present invention is a coating for dual curing application. The coating a polyisocyanate component and a polyol component. The polyol component includes a dual-curing component in an amount ranging from 2 to 10 part per weight of the non-activator component, at least one solvent in an amount of 50 to 70 parts per weight of the polyol component, an optical brightener in an amount of 0.01 to 0.03 parts per weight of the polyol component, thixotropic additive in an amount of 2 to 8 parts per weight of the polyol component, an adhesion promoter component in an amount of 0.25 to 1.0 parts per weight of the polyol component, and a polyester resin in an amount of 20 to 40 parts per weight of the polyol component.
Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.